Overhead Mixers
An overhead mixer or stirrer blends components by spinning a long shaft with blades or other mixing elements. The shaft can be raised or lowered for larger or smaller containers. The mixer's speed, direction, and duration of mixing can be adjusted based on the specific requirements of the materials being processed.
Some important points to consider when using overhead mixers:
- Wide range of brands and price points available.
- Process variability based on resin viscosity, diameter of container, diameter of mixing blades and amount of resin being mixed.
- Compatible with a wide range of mixing containers.
- Requires purchasing several accessories for optimal operation.
- Open mixing container.
- Mixing capacity up to 15,000 g
Max Capacity | Hands-On Time | Machine Time | Total Process Time | Equipment Cost |
|---|---|---|---|---|
15,000 g | 4 minutes | 10 - 26 minutes* | 14 - 30 minutes* | $$ |
* Total processing time varies according to the amount of resin being mixed. 3000 g would mix in about 10 minutes while mixing the maximum amount of 15,000 g would take approximately 25 minutes.
Overhead mixer
An overhead mixer is a device that spins a blade to mix. It operates much like a drill press. An adjustable chuck secures the shaft of the mixing blade
- A built-in timer is recommended.
- Models with more power/torque may be needed for larger volumes and higher viscosity resins like RPU 130.
- The following models are provided as reference.
Model | Capacity | Price |
|---|---|---|
All resins up to 3 L. Lower viscosity up to 10 L. | $$ | |
All resins up to 3 L. Lower viscosity up to 10 L. | $$ | |
All resins up to 10 L. | $$$ |
Contact your Carbon representative if you have questions.
Standard quad-axial propeller blades can be used for both pigment dispersions and component mixing.
- Size is important: Larger mixing blades are required for larger volumes.
- One piece blades (shaft + blade) are more durable and easier to clean than two part blades. But they can be significantly more expensive.
- Two part blades (blade + shaft) are less expensive but less durable.
See the table below for recommended one piece mixing blades.
Model | Notes | Price |
|---|---|---|
Ideal for volumes below 600 mL | $ | |
Best for 500 mL to 3 L | $ | |
For larger volumes - 1 L to 15 L | $ |
Choosing the correct blade size is important. The ratio of the blade diameter B to the mixing container diameter C should be 0.33 - 0.6 for optimal mixing.
0.33 < B / C < 0.6
For example, for a 100 mm diameter blade, the mixing container should be between 166 mm and 300 mm in diameter. A blade that is much smaller or larger than the container can result in a poor mix which affects the final part quality.
Stand
The stand securely holds the overhead mixer above the mixing container.
- Telescoping stands are highly recommended. They are slightly more expensive but are much easier to use than static stands. The mixers are heavy and the easy adjusting stand is very helpful and worth a small premium.
Strap clamp
This device is an adjustable belt that securely holds the mixing container in place during mixing.
Example: RH 5 Strap clamp
Mixing container
- PPE or HDPE containers are recommended.
- Transparent or natural containers are recommended so that it is easier to inspect resin during mixing.
- The container must be large enough to hold the resin components to be mixed.
- Remember to consider the diameter of the mixing blade. See Propeller mixing blade above for more information about sizing.
Rubber pad
In combination with the strap clamp, the pad holds the mixing container in place during mixing.
The following information is a general guide for usage. Consult your overhead mixer product manual for specific instructions about operation.
Prep the mixer
- Check that the blade is securely installed. If necessary, use the chuck key to tighten the chuck.
- Raise the mixer on the stand so that the mixing container can fit under the blade.
Position the container
- Center the container under the blade.
- Place a rubber pad or other non-slip item under the container.
- Secure the mixing container with the strap clamp to ensure that the container doesn’t spill or move during mixing.
Lower the blade into the container
- Lower the mixer until the blades are approximately one-third the distance from the bottom of the container to the top of the resin surface.
Start the mixer
- Start the mixer at a low speed (~200 RPM) and increase until a healthy vortex is created.
- For smaller quantities, a vortex may not be created.
- If the container is wobbling, adjust the position so that it is centered under the mixing blade.
- For lower torque mixers, it may be necessary to run at a low speed until Parts A & B have incorporated. This will lower the overall viscocity and allow for higher speeds.
- Set the mixing time.
- Mixing time for up to 3000 g would be approximately 10 minutes.
- Mixing time for the maximum capacity of 15,000 g would be approximately 25 minutes.
Check and dispense
- Once mixing has finished, check to ensure that the components have thoroughly mixed.
- Dispense the mixed resin into the cassette and begin printing promptly in order to maximize pot life.
